Make dressing. In a bowl, combine miso, lemon juice, honey, vinegar, and sesame oil. Season with salt and pepper. Slowly whisk in oil until combined.

Bring a pot of water to a boil. Add noodles and cook until tender, 6-8 minutes. Drain noodles and rinse with cool water. Set aside.

Meanwhile, bring another medium pot of water to a boil. Fill a bowl with ice water and set aside. Add broccoli to boiling water and cook until just bright green, 2-3 minutes. Remove with a slotted spoon and place in bowl of ice water. Once chilled, remove broccoli and pat completely dry.

Pat noodles completely dry and add to a large bowl along with broccoli, scallions, and carrots. Toss with enough dressing to coat. Top with sesame seeds and serve.